Thanks for your feedback! To be honest I haven't play chess for a long time and I didn't realize that bishop cannot jump over other figures. Now I see it is confusing. My bad...
Bishop's part is made in hurry. I just wanted to have more than one promotion in the jam version.. maybe the knights part would be enough for the jam entry. And if the bishop wouldn't jump over the wall, without introducing another mechanics like shifter plates you talked about (good idea btw.), this part would be absolutely straightforward.
Anyway, all feedback is really appreciated and I will definitely use it in extended version in the future.
Thanks a lot!